Yeah I agree every area is different. These same guys run a 970 with a 504 in it with a 2670 pump turned up with a 3Lm turbo other than that its stock. They have no problem with it. They do extremely well with it against built tractors and have no problem at 10mph in 6th gear. In our area setup is more important than big power. Yes the heads are the same except the later one use thread in injectors.